diff --git a/app/indexers/app_indexer.rb b/app/indexers/app_indexer.rb
index cb70b6f2d..f523852f6 100644
--- a/app/indexers/app_indexer.rb
+++ b/app/indexers/app_indexer.rb
@@ -30,12 +30,23 @@ def full_text(file_set_id)
   end
 
   def add_date(solr_doc)
-    # The allowed date formats are either YYYY, YYYY-MM, or YYYY-MM-DD
-    # the date must be formatted as a 4 digit year in order to be sorted.
-    valid_date_formats = /\A(\d{4})(?:-\d{2}(?:-\d{2})?)?\z/
     date_string = solr_doc['date_created_tesim']&.first
-    year = date_string&.match(valid_date_formats)&.captures&.first
-    solr_doc['date_tesi'] = year if year
-    solr_doc['date_ssi'] = year if year
+    return unless date_string
+
+    date_string = pad_date_with_zero(date_string) if date_string.include?('-')
+
+    # The allowed date formats are either YYYY, YYYY-MM, or YYYY-MM-DD
+    valid_date_formats = /\A(\d{4}(?:-\d{2}(?:-\d{2})?)?)\z/
+    date = date_string&.match(valid_date_formats)&.captures&.first
+
+    # If the date is not in the correct format, index the original date string
+    date ||= date_string
+
+    solr_doc['date_tesi'] = date if date
+    solr_doc['date_ssi'] = date if date
+  end
+
+  def pad_date_with_zero(date_string)
+    date_string.split('-').map { |d| d.rjust(2, '0') }.join('-')
   end
 end
diff --git a/spec/indexers/app_indexer_spec.rb b/spec/indexers/app_indexer_spec.rb
index 9d96ece20..a771964c3 100644
--- a/spec/indexers/app_indexer_spec.rb
+++ b/spec/indexers/app_indexer_spec.rb
@@ -24,4 +24,62 @@
       expect(solr_document.fetch("account_cname_tesim")).to eq(account.cname)
     end
   end
+
+  describe "#generate_solr_document" do
+    context "when given a date with a YYYY-MM-DD format" do
+      it "indexes date_ssi in YYYY-MM-DD format" do
+        work.date_created = ["2024-01-01"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01-01")
+      end
+    end
+
+    context "when given a date with a YYYY-MM format" do
+      it "indexes date_ssi in YYYY-MM format" do
+        work.date_created = ["2024-01"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01")
+      end
+    end
+
+    context "when given a date with a YYYY format" do
+      it "indexes date_ssi in YYYY format" do
+        work.date_created = ["2024"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024")
+      end
+    end
+
+    context "when given a date with a YYYY-M-D format" do
+      it "converts the date to YYYY-MM-DD format and indexes date_ssi" do
+        work.date_created = ["2024-1-1"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01-01")
+      end
+    end
+
+    context "when given a date with a YYYY-M format" do
+      it "converts the date to YYYY-MM format and indexes date_ssi" do
+        work.date_created = ["2024-1"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01")
+      end
+    end
+
+    context "when given a date with a YYYY-MM-D format" do
+      it "converts the date to YYYY-MM-DD format and indexes date_ssi" do
+        work.date_created = ["2024-01-1"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01-01")
+      end
+    end
+
+    context "when given a date with a YYYY-M-DD format" do
+      it "converts the date to YYYY-M-DD format and indexes date_ssi" do
+        work.date_created = ["2024-1-01"]
+        expect(solr_document.fetch("date_ssi")).to eq("2024-01-01")
+      end
+    end
+
+    context "when given a date with an invalid format" do
+      it "indexes the given date" do
+        work.date_created = ["Jan 1, 2024"]
+        expect(solr_document.fetch("date_ssi")).to eq("Jan 1, 2024")
+      end
+    end
+  end
 end